1978 C3 Wiper Delay

[John Frank]

On the 1978 Corvettes with the pulse delay wiper option (RPO CD-4)a bypass circuit board replaces the wiper fuse. A prior owner yanked this circuit out and really screwed up the wiper system. I have gotten everything pack to spec except I need the bypass circuit board that replaces the wiper fuse. Any suggestions on where I might get this? None of the normal sources I've tried has it.

[Joe L.]

Re: 1978 C3 Wiper Delay

John-----

I don't know of a "circuit board", per se, that plugs into the fuse panel in place of the wiper fuse for 1978 Corvettes equipped with the CD-4 pulse delay wiper. What plugs into the fuse panel for CD-4 installations in place of the wiper fuse is the connector for the controller. A short harness which is part of the controller connects the controller to the fuse panel. The controller, itself, is located behind the forward console.

The original controller for your car was GM #470318. That part was discontinued in November, 1979 and replaced by GM #14005004. Unfortunately, that part was discontinued without supercession in January, 1994. This could be a very difficult part to locate, as you've found. I'd recommend trying a used parts source like Pacific Corvette in Puyallup, WA, Contemporary Corvette in Bristol, PA, or Steve Arcoleo in New York. I don't like buying used electrical parts but I think that this will be your best option.

Pacific Corvette inventories their used parts by GM part number. So, all you should need to do with them is give them the 2 part numbers I provided here and they should be able to tell you if they have either one.

[Joe L.]

Addendum

By the way, it just occurred to me that it's very possible that the controller is still there and just the wires and/or connector have been cut. If that's the case, it should be easier to obtain what you need.

[John Frank]

Re: 1978 C3 Wiper Delay

Thanks, Joe. The controller was still installed. The item that plugs into the fuse block in place of the wiper fuse may just be a connector but the GM wiring diagram refers to it as a circuit board. That connector/circuit board was wired to the controller with a brown and yellow wire. The brown wire is the hot lead from the fuse block and had a in line fuse in it. The yellow wire is the return from the controller.

What a previous owner has done is cut the wires going to the connector/circuit board and removed the connector/circuit board and the inline fuse. The brown and yellow wires were then wired into the hot lead for the door locks for who knows what reason. That really screwed things up.

I am reasonably sure that the controller is functional when properly wired. If I can get hold of a connector/circuit board I can restore the system to original. Having the connector/circuit board come with the wires and in line fuse holder still attached would be a plus however I can duplicate those if I have to.

To duplicate originality I really only need the connector/circuit board so taht is what I am lookikng for.

[Joe L.]

Re: 1978 C3 Wiper Delay

John-----

Looking at a wiring diagram that I have, I don't see any indication of a circuit board located at the fuse block---just a connector with an in-line fuse. If there is some sort of special connector with an integral circuit board, that will make for a real problem. No such piece was ever available in SERVICE from GM. The connector, if it included a special circuit board assembly, was supplied only as part of the controller assembly. In order to get the "connector" you then need, you'll probably have to locate the entire controller and purchase it. I can't imagine that anyone with the controller is going to want to cut of the end of the pigtail and sell just that part to you.

If, on the other hand, the connector at the end of the pigtail is a connector only, then it may just be possible to obtain a replacement. GM services a wide array of electrical connectors and it's just possible that the one you need is still available. The problem is identifying it. The connectors are not cataloged by specific application.

[Jack H.]

From ST-359-78

The power pickup at the fuse box for RPO CD-4, Pulse Wipe, is annotated:

"Remove Wiper Fuse From Fuse Panel & Insert Circuit Board"

The schematic diagram shows the power connector to be a simple circuit board with two traces on it to mechanically resemble the contact tips of a fuse. So, I think it's a game of semantics as to whether this is a 'connector' or a 'circuit board'.

The wiring IS as described above with brown and yellow wires running from the connector/circuit board at the fuse panel to the pulse wiper's controller and brown wire sporting a 25A in-line fuse. Unfortunately, no other vehicle in the Chevy line-up for '78 has a similar configuration and I doubt there was much need to inventory this part as there are no components on the 'circuit board' to fail....

I'd say you either have to find a Corvette 'bone yard' for the missing part (Paragon, Pacific, Etc.) or improvise a replacement fuse panel plug-in which shouldn't be hard.

[Joe L.]

Re: From ST-359-78

Jack-----

Yes, the GM #470318 and 14005004 controllers were Corvette-only pieces and were used only for the 1978-79 model years. That doesn't help availability, at all. It's possible, though, that controllers used for other models during this period could be modified to work for a Corvette. I suspect that there was significant commonality to them with relatively minor differences. The problem is finding out what those differences, however small, were.